1. Field of the Invention
The present invention relates to a circuit structure of a touch display device, in particular to a circuit structure that shares an electrode between a touch portion and a display portion of an in-cell touch display device and integrates a touch scanning circuit and a display scanning circuit on a substrate so as to save the routing area and the structure space for reducing cost.
2. Description of the Related Art
Due to the evolution of the display technique, the screen evolved from earlier on the Cathode Ray Tube (CRT) to the main stream nowadays, Liquid Crystal Display (LCD). The LCD has the advantages of light weight and small size, the image quality thereof is not worse than the CRT. Therefore, after the mass production, LCD speedily holds the most part of the display market. Up to the present, many kinds of LCD are developed. A thin-film transistor LCD (TFT-LCD) makes use of thin-film transistor technique to improve the image quality and is related to an active matrix LCD that is applied in televisions, flat panel displays, and projectors. The panel of the TFT-LCD is defined as a layer of liquid crystal placed between two glass substrates. The upper layer of the glass substrates is a color filter, and the bottom layer of the glass substrates includes a transistor, through which an electric current is passed and results a variation of electric field and deflection of liquid crystal molecule so as to change the polarization of the light and determine the shading value of the pixels via a polarizer.
A touch panel makes use of a sensorial device using a multi-touch contactor such as fingers or pen point to input a signal. The device mainly comprises a pressure plate having a high sensitivity to the exerted pressure. When an object exerts a pressure, the pressure plate generates an analog signal. The location of the pressure source is located via a sensorial electrode, and then the controller transforms the analog signal into a digital signal that is acceptable for the system. Further, the touch driver of the system integrates each element for compilation and results in a respective effect, which is then output for generating efficiency such as pressing a button or an operating apparatus. A touch display device is resulted after combining the two techniques of touch panel and LCD so as to integrate the display function and the touch function. The button or dialog box displayed on the screen is operated by touch. Therefore, when users touch the figured button on the screen, each connecting device is actuated according to the pre-compiled program, thereby replacing the mechanical button panel. After pressing the button, users receive a related suggestion or information via the screen. Moreover, it is convenient to add or adjust the related functions of the button without remaking a new button panel. The tablet personal computer, the most popular device nowadays, is mainly operated by touching and omitting a mouse and a keyboard thereby greatly improving the weight of the device body and the operation.
Referring to FIG. 1, a structural view of the conventional touch display device is shown. A touch substrate 11 is disposed at the top layer, a color filter substrate 12, a RGB layer 13, a common electrode 14, a liquid crystal layer 15, a display TFT array substrate 16, and a display TFT substrate 17 are sequentially disposed thereunder, thereby integrating the touch and display functions to become a touch display device. However, the thickness of the touch display device is increased because the touch display device is superposed by the substrate layers, each with a certain thickness. For example, the touch substrate 11 occupies a quite large part of the thickness of the touch display device. Nowadays, the situation that everyone has a digital device brings about a tendency of ultra-thin body of the device. Therefore, to integrate the layers of the device structure for reducing the entire thickness is conducive to the tendency and increases the market sales volume.
To solve the conventional structure with a thicker device body, the present invention provides an in-cell touch display device which includes a thinner structure. Under the condition of not affecting the entire operation principle, the display scanning circuit and the touch scanning circuit of the touch substrate are integrated into the display TFT array substrate, and the touch detecting line within the original inner touch substrate is reserved at the original position of the touch substrate. Therefore, the touch substrate structure is dispersed whereby the entire thickness becomes thinner for solving the conventional problem effectively.